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COPyRIGIIT DEPOSm 



SUCCESSFUL 
INCUBATION 



A WORKING MANUAL FOR 
LARGE HATCHING PLANTS 



BY P. COOK 

Proprietor OF the MAMMOTH BA.TCHERY 
LOS ANGELES CvWL. 



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PRICE, ^l.OO NET 



PUBLISHED BY THE 

WEIMAR PRESS 

301i5 S. MAIN ST.. LOS ANGELES.CAL. 



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Copyright, 1 9 
By P. Cook. 



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PREFACE 

A. 



« This little book gives oar experiences in hatching 
conducted for about six years. It is the story of our 
investigations, how we have finally stumbled on to the 
right way to hatch chicks. It is hoped it will save many 
the heart-rending experiences we have gone through. 
When you once know how, it is simple enough to hatch 
chicks, but it is not always easy to find out the simple 
way. 

We also hope that there will be no disappointment 
to our readers. It seems that most poultry books are 
written by persons sitting by a cosy fire spinning theo- 
ries that are utterly impracticable. This book is based 
on actual hatchery work and every effort has been made 
not to mislead any one or make claims unsupported by 
actual facts. 

But there is still room for improvement and we shall 
be glad to hear from our readers if difficulties persist. 
All letters to me should be addressed to the publishers 
of the book, and they will be forwarded. 

The price of the book may seem high to many per- 
sons, but it costs a great deal to publish a book. It is 
not the paper it is printed on, but the advertising that 
costs, and it is more than doubtful whether the pub- 
lishers will ever be adequately paid for it even at its 
high price. It contains real information, that will be 
worth tenfold its price to any reader even the first year 
he uses an incubator. 

Moreover, it must be remembered that all the inven- 
tions of this book are given free to the public, there are 
no patents on any of them. Everybody is at liberty to 
use what he likes. The proceeds from the book is the 
only remuneration the author receives. 

P. COOK. 

Los Angeles. Cal., Jan. 1, 1911. 



DESCRIPTION OF P. COOK'S INCUBATOR 

(See Diagram on Preceding Page) 

Fig. 1. a, jacket enclosing boiler. This communi- 
cates with the outer air around its lower rim. The air 
thus heated by the sides of the boiler passes into the 
upper compartment of the incubator through the open- 
ing e, during incubation there is no other ventilation. It 
will be seen at once that this method procures a great 
deal of superheated air, which helps to take care of the 
evaporation from the eggs without unduly increasing the 
humidity of the egg-chamber, b, small tubes through 
which heat from the lamp, y, passes through the boiler, c, 
when the damper of the regulator is down. When 
damper is raised, the heat passes directly from the lamp 
through the large centre tube, o, without heating it, n, 
is a collar or rim compelling the heat from the lamp 
to ascend through small tubes, instead of dissipating be- 
low the boiler; f, portion of return pipe from incubator; 
d, portion of outflow pipe or coil entering incubator; h, 
thin muslin diaphragm separating upper and lower com- 
partment of incubator, preventing any draft from air en- 
tering at e; k, egg tray; i, nursery; m, incubator legs; 
p, ventilating tube, used to dry off chicks after hatch- 
ing. Kept closed during incubation. 

Fig. II. r, incubator; s, drawer containing nursery 
and egg tray; t, stick on which drawer rests when pulled 
out. 

Note. — All the experiments and successful hatches de- 
scribed in this book have been made with machines con- 
forming strictly to this type. We have so far found this 
the most successful type, and used it equally well with 
hot air as with hot water heating. 



INCUBATOR INSTRUMENTS 

P. Cook's Carbonic Acid Gas Test, complete set of all neces- 
sary' instruments, $5.00 

P. Cook's Hygrometer, continuous reading, $3.00 

P. Cook's Simplified Hygrometer $ 1 .00 postpaid 

( No one using an incubator should be without at least the 
Simplified Hygrometer. The other instruments are for 
large hatcheries.) 

For sale by P. COOK, 301 7 S. Main St., Los Angeles. Cal. 



Note to page 2 1 —.No carbonic acid gas is given off by the 
body of the hen. We have made many tests to that 
effect. All that is found under her comes from the 
respiration of the embi^yo. 



SUCCESSFUL INCUBATION 



SOME EXPERIENCES WITH INCUBATORS. 

Some of the strangest experiences take place with in- 
cubators. We have had our share of them. The 
very first incubator we bought happened to be a good 
one, and we had reasonably good hatches out of it, yet 
a considerable proportion of the chicks died in the shells. 
We supposed that with more experience we would be 
able to get better hatches, but the contrary proved to 
be the case. After two hatches we moved this incubator 
to another building, and we had nothing but poor hatches 
from it in spite of the best of our care, so we gave up 
that kind of an incubator. Then we heard of one 
that was producing very good hatches through an ac- 
quaintance, and we invested in that make, but it would 
not hatch for us in any way at all. We tried it six or 
seven times, and lost practically every hatch. Then it 
was moved to another room, and as we were badly need- 
ing an incubator to take care of some surplus eggs, we 
decided to run it once more, and the machine has given 
very good hatches to the present date, standing in this 
one place. 

In the meantime we also built different types of in- 
cubators of our own to find out, if possible, the difficulties 
in incubation, and though we constructed over thirty 
different types of machines, and tried almost every con- 
ceivable method we did not seem to make any particu- 
lar headway. It was always the same old story, some- 
times a very good hatch, and then a number of very bad 
ones. We tried it three times with one very popular 
make of incubator, and in each hatch as many chicks 
were dead in their shells as those that succeeded in get- 
ting out. We sold the machine in disgust. The man 
who bought it from us moved it to his house, and the 
machine hatched every fertile egg, although he had never 
run an incubator before. 

We had another machine which we built ourselves 
that gave a very remarkable hatch, and we hoped we 
were nearing the goal. We moved it to another room 
in our hatchery, and it would not hatch there at all. 
And more perplexing still was another case of a ma- 
chine holding about 1000 eggs. It had four drawers, 
and the two drawers in the rear end of the machine 
always batched very well. The two drawers in the other 
end of the machine, while the temperature was the same 
throughout, never hatched at all, i. e., most of the chicks 
died in the shell, or were cripples, though it was im- 
possible to discover any difference in the machine. 

Another peculiar case we had was this: Someone 
brought us some eggs on which a hen had set for four 



days, and then died on the nest. It was about IS hours 
after the hen was dead that the eggs were brought to us, 
and the eggs were stone cold when they arrived. We 
placed them in an incubator with 3 00 eggs in it, which 
had been set just about the same time. At the time of 
hatching we secured nine strong, lively chicks from the 
eggs the hen had set on, and there was only one egg 
which was fertile that failed to hatch of the hen's 
clutch, but the 300 in the incubator practically did not 
hatch at all, i. e., there were about fifty miserable chicks 
that got out. The rest did not get out of the shell at all. 

We have tried a great variety of different makes of 
machines, and we have had the same story with all of 
them. Sometimes they hatch very well, and sometimes 
they do not hatch at all. Most of the time there are 
more dead chicks in the shell than there ought to be 
with all of them. Some machines are far better built 
than others, but even the poorest made machines have 
given us just as good hatches, as the most expensive 
ones. 

The glowing testimonials which all the incubator man- 
ufacturers send out are i)robably genuine, as we could 
duplicate most of them once in a while. Nearly every 
make of machine we have seen sometimes give as good 
hatches as claimed, but there is always against the 
one success a woeful lot of failures. Of course, if eggs 
are exceptionally strong and vigorous in fertility, they 
will perhaps hatch under almost any conditions, but 
the great necessity for poultry raising is to get an in- 
cubator that will hatch nearly as well as the hen, and 
in all our experiences w'ith the hens we have found 
that, barring accident, she succeeds in hatching practi- 
cally all the fertile eggs. We soon became convinced, 
of course, that something must be wrong with the in- 
cubator, but the harder we tried to find out the farther 
we seemed to be from the goal. 

It is easy to build a new incubator, and build one 
that one thinks is a great imi)rovement. Ninety-nine 
times out of one hundred it will be found, however, 
that the new machine is worse than the old one. It is 
needless to rehearse the whole history of our experiences. 
I simply mention these things to show that in the way 
incubators have been constructed hitherto some vital 
things have been lacking, and if anyone has experiences 
similar to these, he must remember that every other 
poultry man is apt to find such happenings some time 
or other. It is true, some poultrymen have been Singu- 
larly fortunate in having almost always good hatches, 
and others have been singularly unfortunate, in al- 
most always having very poor hatches. However, we 
think that, in the following pages we describe a method 
which will enable anyone to secure hatches nearly as 
good as those the hen produces. 

So far as we know we have good reason to believe that 
the essential principles of incubation have been discov- 
ered, and the only thing that remains to be done is to 

8 



reach a greater perfection of our method. At any rate, 
the only way to discover the right method is by un- 
ceasing experiments, and we shall be very glad if persons 
who follow our method will report to us the success, or 
lack of success, which they have. We hope for the heart- 
iest co-operation in this respect, as the first principle 
in successful poultry keeping, is the successful hatching 
of strong, vigorous chicks. 

It is certain that in an incubator where fifty per cent 
of the chicks die in the shell, the chicks that actually do 
get out have not been incubated under desirable condi- 
tions, and must have suffered considerable, which means 
that they are handicapped from the first. 

It is an unfortunate thing that it is almost next to 
impossible to have people willing to acknowledge their 
failures in hatching. Every body seems to think it a 
disgrace to acknowledge the unsuccessful hatching of his 
eggs. It is time that there be a little more honesty 
among poultry men in this respect, and if anyone has 
discovered a successful way of hatching he should be 
willing to let his neighbors know it. 

We believe that we have made very important discov- 
eries and therefore publish this little volume, but we de- 
sire to have it taken as an incentive to more careful ex- 
periments, much rather than as an entire solution of the 
problem. 

The most careful methods are necessary for this in- 
vestigation, and much patience must be exercised, but 
the fact that every once in a while an incubator pro- 
duces perfect hatches shows beyond a doubt that the 
goal of unfailing success is attainable, and if we are 
patient enough and work hard enough we shall finally 
wrest from nature her secrets. 



HOT WATER OR HOT AIR INCUBATORS. 

We have used very extensively in our tests, both hot 
water and hot air incubators, and so far as the hatching 
of eggs is concerned, it makes not the slightest difference 
which is used, providing it is constructed properly. 

Manufacturers of hot water machines should see to it 
that their hot water tanks are well made, and especially 
should avoid any combination of galvanized iron with 
brass or copper, as these are sure to leak in a very short 
time, on account of electrolysis. 

We should advise, however, for all small machines, the 
use of hot air, as we have found in our experience that 
it gives much less trouble. If once such incubators are 
built right, they last practically a life time. The heat 
is not as even in a hot air machine, as it can be made in 
a hot water machine. But a little unevenness of heat 
seems to be of no importance. The hot-air machine is 
less trouble to take care of than the hot water machine. 
However, the hot air machines can hardly be built suc- 
cessfully to take care of more than 5 eggs. If larger 
machines are to be used, hot water is required. 



We have also experimented witli a yreat many differ- 
ent boiler systems, but find a copper boiler with a large 
tube through the center, and a series of small tubes run- 
ning parallel with it between the large center tube and 
the sides of the boiler, to be the most successful. The 
damper is placed over the large center tube connected 
with a thermostat. When the damper rises, the heat 
from the lamp or gas flame passes directly through the 
center tube without heating any water in the boiler. 
When the damper is closed the heat passes up the center 
tube and returns through the smaller tubes before find- 
ing an outlet, thus giving an immense heat surface. 

The requirements for incubator boilers are that they 
should have an immense heating surface when the dam- 
per is closed, and when the damper is open none, or at 
least only a very small amount of heat should pass to 
the boiler. 

The best circulating system we have found to be 
wrought iron pipe connected in the ordinary way to 
the boiler, but the outflow pipes should be connected 
to the top of the boiler, and the return flow should enter 
the bottom of the boiler. The boiler always must be 
placed somewhat lower than the outflow pipes. In our 
practice we place the outflow pipes at the top of the 
boiler, and let them rise gradually about one inch, or 
sometimes two inches to the extreme back of the ma- 
chine, and then let the return pipe have a fall of about 
two inches through the length of the incubator, and then 
let it pass down to the bottom of he boiler. It does 
not make any difference how far the highest point of the 
pipe is from the boiler, as hot water will rise to the top, 
but there must be an even fall from the highest point 
to the return, in order to insure good circulation. 

In hot air machines the difficulty is to spread out the 
heat toward the sides. There are several ways which 
seem to do the work equally well, and a number of differ- 
ent systems are in use on the incubators on the market. 
We cannot see that one has any advantage over the other. 



HINTS TO THE MANUFACTURERS OF INCUBATORS. 

Incubator Case, Doors, Etc. 

There are very few incubators on the market at the 
present day that are built sufficiently well for the pur- 
pose for which they are intended. Many incubators are 
built so cheaply, and in so slovenly a manner that no 
man who cares to hatch eggs should ever be tempted to 
buy them, no matter at what price they are offered. They 
are too expensive even if they were given away. The 
first requirement for success in raising poultry is to hatch 
strong and vigorous chicks, and unless an incubator is 
well built, you cannot possibly do this. It is not the ma- 
terial that is used in the incubator which is of so much 
consequence, but the workmanship in putting it together 
is of the very greatest importance. Every incubator 

10 



should be built of double walls throughout, and at least 
on top, should have a thoroughly heavy packing of heat 
insulating material. But more important than the pack- 
ing is the care with which joints are made. They should 
be made on proper machinery and carefully glued 
together, so as to make the. incubator case air-tight, es- 
pecially the door should be made to fit absolutely air 
tight. This is almost impossible to accomplish unless the 
edges of the door and its casings are lined with felt. 
There should be double doors, one glass door next to 
the eggs, and outside of that a solid wood door. This 
is preferable, for if chicks are kept in the dark while 
hatching they will remain evenly scattered over the in- 
cubator. If there is only one glass door chicks will all 
crowd to the front. This may be obviated somewhat by 
placing the glass high up in the door, and leaving a con- 
siderable dark space at the bottom, which keeps the light 
out of the nursery. But far better than the arrange- 
ment of glass doors, and egg trays is the method of con- 
struction used in our Mammoth machines. These have 
simply a large drawer, which fits tightly in the machine. 
The egg trays are placed within this drawer, near its 
top, and for airing the eggs, the whole drawer is pulled 
out of the machine resting one end upon the incubator, 
and the other on a stick fastened to the front of the 
drawer. A small window screened with curtains is cut 
in the upper part of the drawer through which the tem- 
perature may be read, and chicks may be watched at the 
time of hatching. This arrangement saves a very large 
amount of labor, as the chicks can easily be gotten out, 
and the eggs are always protected from drafts, as the 
sides and bottom of the drawer are solid, and thus pre- 
vent any drafts from striking the eggs. 



THERMOSTAT, LAMPS, ETC. 

It is immaterial v/hat kind of thermostat is used, 
whether it be composed of different metals, or ether 
wafers. Everything here, as everywhere else, depends 
upon the care with which they are made. Either kind 
will last a life time, if well made, but it is quite important 
that all the bearings should have knife edges and should 
be patterned after the method of bearings used in weigh- 
ing-scales. 

When possible only one direct lever should be used, 
and the method of regulating the heat should be that 
which is commonly known as the damper method. Any 
thermostat working on the v/ick of the lamp is always 
more or less unreliable, as the wick sleeves are sure to 
char some time or other, and thus prevent its working. 
While there is a little saving of oil on the lamp trips, 
they are sure to spoil the hatch sooner or later, and thus 
may be expensive in the end. 

Lamp bowls should be made either of galvanized iron 
or copper or brass, and they should be well and strongly 

II 



made, and the upper part of the lamp bowl should be po:- 
fectly smooth, sloping toward the edges, so that no oil 
will stand on it. 

If the boiler of the incubator is constructed properly, 
arrangements to keep water on the lamp, or around the 
flame are unnecessary, and had better not be used. The 
final outlet of the bad air from the lani]) should be at 
least twelve vertical inches above the flame, no matter how 
far endways, or sideways this outlet is found. Other- 
wise there will be heating of the lamp flame, and of the 
lamp bow], and there is danger of generating explosive 
gases. 

Lamj) chimneys should be made of iron with a large 
mica window at least 2 inches in diameter, but see that 
your chimneys are faultlessly made, for drafts from the 
chimneys will cause the lamp-flame to smoke, and be- 
come dangerous. The lamp on any incubator should be 
carefully locked. No si)ring arrangement is ever to be 
allowed, for springs, no matter how good they are, will 
get weak in a short time, and the lamp will not fit prop- 
erly. The lamp should be so securely locked to the in- 
cubator that it cannot be knocked off; even if the incu- 
bator should be overturned the lami) should still stick 
to it. To encase the incubator in metal is useless, the 
danger comes from the lamp, not from the incubator. 
Common sense requires these precautions. 

Thermostats should have a protective covering so that 
cats and dogs, or children or plaster that may fall from 
the wall on them, would not throw them out of position. 
It is to be remembered that any thermostat must of ne- 
cessity be a delicate instrument, and it should be made 
accordingly, and treated accordingly. 



CARE OF BREEDING STOCK AXJ) FERTILITY 
OF EGGS. 

We have used eggs from birds kept under all sorts of 
conditions. Birds that have run on the wide range, and 
birds that for several years have been confined in very 
small pens, also eggs from birds fed on i)ure grain and 
birds that were fed on nothing but garbage. We have 
not been able to detect any dilTerence in the fertility, and 
vigor of the embryo in the eggs, as far as external condi- 
tions and feeding of stock is concerned. More seems to 
depend upon the vigor of the fowls, and especially the 
males. Males should have a rest some time during the 
year, or should be interchanged with others. This much, 
however, is certain, that birds kept on a very large range 
have the best chance of producing vigorous strong germs 
in the eggs intended for hatching, but it must remain 
for further experiment whether confining birds or diff- 
erent methods of feeding affect the vigor of the embryo 
in the eggs. 



CARE OP THE EGGS. 

One of the first requirements for successful incubation 
is the proper handling of the eggs. Eggs should be gath- 
ered as soon as they are laid, and not exposed to the heat 
or bright sun. They should be carefully placed in the 
ordinary market egg cases, and should be kept in a cool 
place (55 degrees), but under no circumstances should 
they be exposed to draft of any kind. The fresher the 
eggs are, the better they will hatch. 

If it is expected to hatch every egg that is placed in 
the incubator, no eggs over three days old should be 
used. However, we have sometimes had reasonably good 
results from eggs that were three and four weeks old. 
There is a popular idea that eggs intended for hatching 
should be turned every day. We doubt very much if this 
does them any good. It is of much more importance to 
handle the eggs very gently, for the jarring and shaking 
of them is a heavy strain on the various membranes of 
the egg. Violent shaking of the egg will destroy all its 
possibility for hatching, and the less eggs intended for 
hatching are handled, the better it is. 

If eggs have become soiled, they should be washed, but 
it would be better not to use any eggs that have been 
washed, or subjected to any unnatural conditions in any 
way. A clean egg gathered from the hen's nest and 
placed immediately in the incubator has tremendous 
chances over an egg that has been more or less abused. 

Defective eggs, and those with round ridges through 
the middle, or rough shells, or imperfectly formed shells 
had better be discarded, as well as very small or very 
large eggs. They will hatch very well at times, but 
the chances are somewhat against them of producing a 
perfect chick. Remember, do not expose your eggs to 
the sun. Keep them cool, (about fifty or fifty-five de- 
grees), but do not chill them, and above all handle them 
very gently, and keep them out of the draft. 



13 



THE PROCESS OF INCUBATION 



THK KKillT TKMPKKATIKK l-'OK INCUUA.TION 

We have made a large number of tests of the temper- 
ature of eggs under the sitting hen. It is rather diffi- 
cult to arrive at any exact temperature. The eggs on the 
outer edges of the nest are usually considerably colder 
than those in its centre, but as she shifts them around 
a great deal, all the eggs receive the highest temper- 
ature which she produces sometime or other during the 
day. 

If the thermometer be placed among the eggs, we have 
not generally found it to register over 100 to 102 degrees. 
If the thermometer be applied to the hen's body, we 
have quite often found a temperature of 104 to 107 de- 
grees. Great care must be exercised in taking the hen's 
temperature, for as soon as she gets the least worried, her 
temperature rises rapidly, and often in a few minutes reg- 
isters lOS degrees or more. Even a non-broody hen, 
with normal temperature of 98 will soon rise to 102 if 
agitated. 

The safest method of arriving at the temperature of in- 
cubation under the hen is to thrust a sensitive ther- 
mometer quickly into the middle of the egg taken from 
the center of her nest. Numerous tests which we have 
made in that way, always range closely between 102 and 
104 degrees. Upon the whole, perhaps no better incu- 
bating temperature can be found than 103 deegres. 

In our practice the thermometer bulb is placed level 
with the top of the eggs, and either left in contact with 
the eggs, or very close to it, and the eggs are incubated 
throughout the hatch from the beginning to the end 
at 103 degrees. Under this temperature if the eggs are 
fresh, chicks are almost always all hatched at the end 
of the twentieth day. Sometimes, if weak, or old, they 
will not hatch till the 21st day or later. 

It is very important that the temperature be 103 de- 
grees at the very beginning and should not drop below it 
during the first six days. After being placed in the ma- 
chine eggs should reach 103 in three to five hours 
If it takes longer to reach the proper temperature, eggs 
are sure to suffer. Nothing is so bad for eggs as say 80 
to 85 degrees of heat for the first day. Some successful 
hatchers even start at 106 and gradually drop down to 
103. Watch your machine the first week as the apple of 
your eye. After that you may sleep in peace. 

Beginners are often needlessly worried if the tempera- 
ture accidentally for a short time drops too low. Eggs 
will successfully withstand quite a considerable amount 
of low temperature, if it comes only once, but they will 

14 



not stand endless see-saws of it. We have successfully 
hatched eggs that accidentally were left out of the ma- 
chine as long as from ten to twenty-four hours, and 
reached a temperature as low as fifty degrees, during 
part of the time. No bad effect seemed noticeable. The 
chicks were perfect. But if there is a see-saw of tem- 
perature, say even between 95 and 105 degrees, for sev- 
eral days, the hatch is usually spoiled. 

Overheating spoils the eggs much quicker than low 
temperature. It depends a good deal on the age of the 
embryo, how fatal overheating will prove. Up till the 
6th day a temperature of 110 for several hours will 
probably kill all the germs, though we have had them 
withstand this for fifteen minutes or so, but where they 
were exposed to this temperature for a longer period, 
we always found all embryos dead. 

We have one case on record, however, where the in- 
cubator, by accident, had reached 115 degrees (end of 
7th day of incubation), and stood at this probably for a 
full hour or more. We only lost about 10% of embryos. 
These all died within the next day. All the rest of the 
embryos hatched perfectly, there were neither cripples 
nor weaklings of any sort. 

CRIPPLES. 

Neither overheating nor chilling the eggs will cause 
• cripples. We have never found any other cause of crip- 
ples than drafts in the machine or too cold a bottom in 
the nursery. We had one case where the incubator 
hatched reasonably well, but 65% were cripples. It was 
found the bottom of the nursery registered only 75 de- 
grees. For the next hatch the nursery was filled with 
straw and cotton batting, and no cripples appeared. 
Perhaps the under side of the egg being so much colder, 
retards the growth of the embroyo on that side, or chills 
it, and thus deranges the normal development of the 
chick. 

It has been claimed that lack of turning causes crip- 
ples, but we have not found it so. In one of our tests, 
one half of the incubator was not turned at all during the 
entire period of incubation and the other half was turned 
three times a day. The half of the incubator which was 
turned hatched normally. The half that was not turned 
at all, hatched but very few chicks, but there were hardly 
any cripples. Most of the chicks grew to maturity, but 
did not get out. Many died during the second week, but 
not a single germ was stuck to the shell. In the half 
that was turned, there was one germ stuck to the shell. 
Evidently turning or not turning has nothing to do with 
germs sticking to the shell. Such germs are defective. 
They have risen to the top and in some way become at- 
tached to the shell, but probably not till after they 
were dead. Their death is probably the cause of adher- 
ing to the shell. At any rate, such could not have been 
saved by turning. Ill-fitting doors will almost certainly 
cause cripples in cold weather. 

15 



TIKNING THE EGGS. 

Our present practice is turning the eggs twice daily, 
twelve hours apart, as nearly as possible. We have had 
very successful hatches, however, where the eggs were 
turned only once a day, and we have even had really 
good hatches where the eggs were turned only five times 
during the entire period of incubation, but upon the whole 
our experience tends to show that turning twice daily 
brings decidedly the best results, i)roviding a mechanical 
turner is used. If the eggs cannot be turned in the ma- 
chine without ojiening it, they should not be turned at all 
for the first three days, and thereafter only once a day, 
for only strong eggs will stand opening tne machine twice 
a day, all the weaker ones will die in the shell or hatch 
with protruding entrails, unabsorbed yolk, etc. 

THE MECHANICAL TUKXER. 

The mechanical turner was used years ago, but proved 
a failure. For that reason it was one of the last things 
we tried. But one day after a miserable hatch, such as 
might even make a strong man almost come to tears, 
we sat down dejectedly in the woodshed by the old hen, 
trying to make up our mind whether to abandon the 
whole wretched hatching business or to try it blindly once 
more, we noticed that she shifted her eggs around every 
20 minutes or half hour, but she did not get off the nest 
to do it. She seemed to hug her eggs all the closer while 
she turned them. This was a lesson, we had not watched 
nature close enough in this respect. We built a turning 
rack, so that we could turn eggs as did the hen, without 
exposing them to the outer air, and in our very next hatch 
we suddenly found ourselves much nearer the goal. The 
easiest way to make such a mechanical turner is to use 
thin strips of wood 14-inch thick and about % -inches 
wide. Make a rack of these to fit closely into your in- 
cubator tray after the manner of a ladder with the rungs 
about 1 % inches apart. The side of your rack parallel 
with the rungs should be two inches shorter than the 
tray, so that this rack can slide forward and backward 
upon the tray. The eggs are placed between the rungs 
and when the rack is moved forward or backward all 
the eggs are turned. The rungs of course are nailed so 
that when the rack is placed upon the tray, the side or 
the rungs is at right angles with the bottom of the tray. 
A thin strip of wood nailed on the top of the wire-bot- 
tom of tray on its sides makes a nice rail for the rack 
to slide upon. Small holes can easily be bored through 
the door of the incubator through which one or two 
small wire hooks can be inserted to pull or push the turn- 
ing rack forward or backward without opening the door 
of the incubator. A plug must be inserted in the holes 
after turning. This turning-rack takes up some space 
and not as many eggs will go into the machine, as with- 
out it, but you will get more chicks out of the machine 
by using it . 

16 



It seems that so simple a thing as this ought to have 
been found out long ago, but apparently it was not. It 
took us six weary years to discover this as well as other 
things. The success and failure of a hatch sometimes de- 
pends on very little things. There are a thousand wrong 
ways to hatch eggs, we know a good many of them. 
There is only one right way, we hope we have discovered 
that in part at least. Remember, turn your eggs twice 
a day, but never open your machine more than once a day. 
Never! 

TESTING EGG8. 

In our practice the incubator is opened for the first 
time on the 84th hour. The eggs are taken out and 
tested. The tray is set on a table with a blanket placed 
under the tray to protect the eggs from cold air circling 
around underneath them. They are left exposed on top 
We are using a 16 candle power electric light bulb en- 
closed in a tin globe (can be made out of a baking powder 
can), which has tv/o round openings one inch in diam- 
eter. The eggs are held up two at a time, one against 
each opening, when their contents may be clearly seen. 
A darkened room must be used. When no electric light 
is available, the best method is to make a tube about 
fourteen inches long of black paper, roll it into funnel- 
sliape with the smaller opening about 1 % inches in di- 
ameter and the larger about six inches. Take an egg, 
place it against the small end, hold up to sunlight, and 
look through the large opening, the embryo may then be 
clearly seen. Practice will soon teach to distinguish be- 
tween the fertile and infertile egg. 

Whatever method is used, care must be taken in hand- 
ling the eggs very gently, and they should never be ex- 
posed to strong light except for the briefest possible mo- 
ment, nor should they be suddenly taken from a dark in- 
cubator into the glaring sunlight. 

It should be remembered that the hen generally hides 
her nest, and eggs are never exposed to strong light. 
While it is not known what damage might result from 
exposure to strong light, it is not likely that nature has 
made any provisions against it. Whatever is done with 
eggs, be careful not to transgress upon nature's methods 

COOLING THE EGGS. 

We have not come to any conclusion as to the length 
of time eggs should be cooled. The investigation of de- 
sirable hatching conditions has been so exceedingly ted- 
ious, and in order to arrive at certain results only one 
thing can be taken up at a time. It is undoubtedly best to 
follow the natural method as closely as possible, asthehen 
does not leave the eggs more than once a day for over 
five to fifteen minutes, and the cooling of the eggs for a 
similar length of time probably comes as near being right 
as possible. Under no conditions should the eggs be 
cooled more than once a day, or be removed from the ma- 
chine more than once in 24 hours. 

17 



INFERTILE EGGS. 

About the t'ounh day the embryo will appear in spider- 
like form in the fertile egg, the red blood veins issuing 
from the centre in all directions. This is the natural ap- 
pearance of a vigorous germ. Where the veins have run 
together into a bloody streak, the germ is dead. Experi- 
ence alone will teach to distinguish between living and 
dead germs during later periods of incubation. An 
infertile egg shows perfectly clear before the tester, ex- 
cept that in white-shelled eggs the yoke may be clearly 
seen. 

The object of testing eggs is to secure the Infertile 
eggs. If eggs were not much more than three days old 
when put in the machine, these infertiles that are perfect- 
ly clear are practically as good as any other egg not over 
seven days old. However, they should not be sold for 
fresh eggs, but they are excellent for baking, cooking, 
etc., and are decidedly superior to storage eggs. In 
testing the eggs for fertility, they should be taken from 
the incubator without turning, the germs will then all be 
found lying on the upper side of the egg. They should 
be held up to the light and if turned at all, it should 
be done gently. 

After all the infertiles have been removed, these latter 
should be re-tested to get the perfectly good eggs. Hold 
the egg up to the tester, then give it a quick jerking turn, 
if the egg looks watery then, it is no longer good. It needs 
experience to distinguish good from bad eggs. Break 
open enough till you find out. 

HOW TO TELL INFERTILE EGGS. 

There is absolutely no way to distinguish a fertile from 
an infertile egg without incubating it for some days. All 
advertisements to this effect are frauds pure and simple. 
Nor can the difference be found out by breaking open the 
egg. There is a white spot, the germinal vesicle, in each 
and every egg laid by hen or pullet, but many an amateur 
cannot discover it, and he thinks what he does not see 
is not there. This germinal vesicle looks precisely the 
same to the naked eye in the impregnated or unlmpreg- 
nated egg. Under the microscope the difference may 
be seen. The germinal vesicle in the unimpregnated egg 
is a simple cell, in the pregnated egg there is a ridge, or 
row of cells, but several days, and staining fluids are 
required to prepare an egg for microscopical examina- 
tion. 

VENTILATION OF EGGS IN THE INCUBATOR. 

Perhaps there is no subject about which there are more 
wild theories rampant than the question of ventilation. 
As one reads the various incubator catalogs, he is sur- 
prised at all the so-called wonderful discoveries each man- 
ufacturer has made. Nevertheless, nobody ever seems 
to have made any sort of an investigation that would 
pass muster in a scientific laboratory. 

18 



There has been a constant reiteration of the great ne- 
cessity of fresh air, but nothing has proved so costly to 
us as the apparent reasonableness of these theories. For 
many years we believed this firmly and sacrificed about 
$2000 worth of eggs to it. 

Many an incubator have we built to improve ventila- 
tion, but the results have been exceedingly disastrous. 
In not a single case have we had a fair hatch where any 
large amount of air was admitted into the machine 
After some years of experimenting we finally invented a 
device by which to test conveniently the relative amount 
of carbonic acid gas under the hen and in incubators. 
We were very greatly surprised as soon as we tested con- 
ditions under the hen. We found the carbonic acid gas 
under her very great indeed, much greater than in any 
incubator. We also discovered at once that the incu- 
bators with the least ventilation, showed much more car- 
bonic acid gas than those pets of ours with much ventila- 
tion. And the hatches from the incubators with poor 
ventilation proved very, very much the best. 

We also had one machine that had been a puzzle for 
a long time. It was made in a very crude manner by 
somebody and was a forbidding looking affair. We 
had purchased it from one of our customers unseen, or 
we certainly would not have bought it. But we had 
bought several hatches of remarkably fine chicks from 
this machine and so we risked it with eggs. We had 
a fine hatch and it was run many times and never failed 
us. The machine had a capacity of about 800 eggs and 
had only one 1-inch opening for ventilation, which was 
screened with two layers of burlap. When the carbonic 
acid gas test was applied to this machine, we found it con- 
tained by far the greatest amount of any machine in the 
hatchery. So far it was hardly possible to doubt that 
too much ventilattion was the cause of many failures. 
We shut up the ventilators on our machines and stuffed 
up all cracks and quite remarkable improvements appear- 
ed at once. The chicks were much stronger and larger. 

We thought perhaps the air-space surrounding the 
eggs was too large, as even with our best incubators 
we could not equal the hen in carbonic acid gas. We 
then built an absolutely air-tight machine cf galvanized 
iron throughout, that had almost no extra air space and 
no nursery. This would even beat the hen on carbonic 
acid gas, but we were never able to reduce its moisture 
much below 90 on the wet bulb, and every hatch proved 
a dismal failure. But undoubtedly not on account of too 
much carbonic acid gas, but on account of too much 
moisture. We found the woodencase with cloth screens 
necessary to produce an incubator sufficiently dry when 
all ventilators are closed. 

We subjoin tables of the tests on carbonic acid gas 
evolved both in incubators and under the hens. These 
tables are the average of a large number of hatches, 
where practically every fertile egg produced a perfect 
chick. They are taken from hatches of eggs during the 

19 



moulting season, when eggs are not naturally very vig- 
orous. We early found that little is to be learned from 
successful hatches from very vigorous eggs. They will 
hatch anyway, and do not reveal the weak points of an 
Incubator. Moreover, a hen was set each time as the 
incubator was set. with eggs taken from the same lot, and 
only such hatches are used in this table where both 
the hen and incubator brought off hatches in every re- 
spect alike, even to the relative weight of eggs and chicks. 
Thus the utmost precaution has been taken to secure a 
standard hatching table. We believe that conditions 
which produce perfect chicks from coniiiaratively weaker 
eggs, must be very nearly ideal. Such are rei)resented in 
our table, so far as temperature, moisture, carbonic acid 
gas and structure of machine is concerned. The values 
obtained were from machines constructed like the one 
shown on page 4. The table for hens are from a 
Barred Rock and a ButT Orpington, sitting in roomy nests 
with straw bottom. It will be seen that the amount of 
carbonic acid gas varies more or less, as also does the 
moisture, and accordingly when neither runs higher or 
lower than any values given, no attention is paid to either 
carbonic acid gas or moisture in our hatchery. It is not 
necessary to have these the same every day so long as 
they come reasonably near this standard. 



STANDARD HATCHING TABLE FOR INCUBATORS. 



D«y <rf_ I Temper I Cubic centi- I Carbonic I Wei 
iDcubatioo J ^ature- | meter* of air I Acid Gai | Bu lb 

1 103 ' 86' 



Peroaat._ <A I Minulet Ess* 
Humidity_ 1 were cooled 

49 



2 


103 






85 


47 




3 


103 






85 


47 




4 


103 






86 


49 


10 


5 


103 


400 


1 


85 


47 


10 


6 


103 


400 


1 


83 


42 


10 


7 


103 


320 


3 


81 


38 


10 


8 


103 


240 


5 


82 


40 


10 


9 


103 


240 


5 


83 


42 


10 


10 


103 


240 


5 


83 


42 


10 


11 


103 


200 


6 


82 


40 


10 


12 


103 


160 


7 


83 


42 


10 


13 


103 


120 


8 


83 


42 


15 


14 


103 


120 


8 


85 


47 


15 


15 


103 


120 


8 


85 


47 


15 


16 


103 


80 


8 


83 


42 


15 


17 


103 


50 


9 


84 


45 


15 


18 


103 


40 


10 


85 


47 


15 


19 


103 


40 


10 


85 


47 


Esst pippins 


20 


103 


50 


9 


92 


68 


Hatrb kalf ow 


21 


103 


40 


10 


84 


45 


Hatch all oul 



20 



RECORD OF TWO HENS 



Oayo( 




1 


2 


1 


2 


1 


2 


1 


2 


Incuba- 


Vol. Ail 


r,a« 


Vol. Air 


r.iii 


Wrt 


Mois- 


Wet 


Mois- 


hen off 


tion 












Bulb 


ture 


Bulb 


ture 


ae& 


1 


















X 




2 
























3 




246__ 


5 


206__ 


6 














4 




240__ 


5 


80__ 


9 


85 


47 






X 


X 


5 


:^ 


240__ 


5 


120__ 


8 










X 




6 


i 


160__ 


7 


80__ 


9 






86 


49 






7 




160__ 


7 


80. _ 


9 


87 












8 


1 


120__ 


8 


80__ 


9 










X 


X 


9 


140__ 


8^ 


120__ 


8 










X 




10 


h-l 


40__ 


10 


40_. 


10 














11 


^ 


40__ 


10 


80. _ 


9 






87 






X 


12 


o 


30 _ 


15 


60__ 


QV. 














13 


t-l 


40__ 


10 


50__ 


9^ 


85 


47 






X 




14 


►li- 


40. _ 


10 


40__ 


10 ' 






84 


45 




X 


15 




30__ 


15 


80. _ 


9 














16 




30__ 


15 


30__ 


15 














17 




30^^ 


15 


20__ 


18 










X 


X 


18 




30__ 
20__ 


15 
20 


20.- 
20. . 


18 
20 





-- 







X 




19 


Chicks Pippins 




20 




20. 


20 


20- _ 


20 






AU through hatching 


21 




















22 S 


with brood of 
s two days old 


-50__ 


9 





The volume of air given in these tables are the num- 
ber of cubic centimeters of incubator air which it took 
to cloud one cubic centimeter of lime water. (The first 
distinct clouding is the point used in the tables.) 
These are exact measurements and should be used in fut- 
ure investigations, to avoid the confusion of different 
standards. The figures for volume of carbonic acid gas 
are an arbitrary graphic representation of its density, as 
indicated on the piston rod of our air pump. They show 
relative, not actual values, but most admirably serve its 
purpose to show the difference between hen and incu- 
bator and different days of incubation. 

The actual amount of carbonic acid gas present in an 
incubator, it should be remembered, is also directly de- 
pendent upon the number of fertile eggs in a given en- 
closed space. These tables are not to be used for the 
purpose of guiding ventilation, in the sense of admitting 
air into the incubator in case there should be found more 
gas than our tables show. Keep your incubator closed 
tightly, no matter how much carbonic gas is found in 
it. We, ourselves, have not been able to obtain any 
higher values, and are of the opinion if we could secure 

21 



a machine giving higher values, it would be still better, 
for as will be seen from the tables giving the records of 
hens, that the amount of carbonic acid gas is much 
greater there. 

It will also be seen that the amount of gas under the 
hens is quite variable, depending upon how closely the 
hen is setting. 

We take it, that these investigations, prove, not act- 
ually how much gas is necessary to hatch eggs, but that 
absolutely confined air is of the very first importance in 
an incubator. If you confine the air in your incubator 
there will always be more or less carbonic acid gas 
present. 

On these measurements human breath shows clouding 
at about 20 to 25 cubic centimeters, or 25 volumes of gas 
on the figures for carbonic acid gas. 

It is noticeable also that even the chicks two days old 
under the hen's wing, live in the presence of much car- 
bonic acid gas. 

Notice also that these hens bringing off perfect hatches 
only left the nest five or six times altogether. In cool- 
ing eggs this fact should be taken into consideration. 



<;p 




3. P. Cook's Carbonic Acid Gas Test. Price, $5.00. 



a, graduated piston rod (for each fifty cc. ) b, air 
pump; c, rubber tube; d, glass tube; e, five cc graduate; 
f, limewater. 

22 



METHOD FOR TESTING CARBONIC ACID GAS. 

Our method consists in withdrawing a certain portion 
of air within the incubator taken directly above the eggs, 
and about twelve inches from the front of the machine. 
A small hole is bored through the frame of the door 
about one quarter inch in diameter, through which a 
small rubber tube with a glass end is introduced. This 
rubber tube is attached to an air pump, holding from 
250 to 300 cubic centimeters of air. The piston of the 
pump is graduated for each 50 cubic centimeters. 

After the air is withdrawn from the incubator, it is 
passed through one-half centimeter of lime water, and the 
point where the clouding of the lime water begins is 
noted. 

As is well known, this clouding is due to the amount 
of carbonic acid gas, which has passed through the lime 
water. The point at the piston is then read, which in- 
dicates directly how many cubic centimeters of air have 
passed through the lime water to effect the clouding. 

The piston rod is graduated up-side-down, beginning 
with 10 and ending with one, so as to indicate directly the 
amount of carbonic acid gas. 

For instance, if the first fifty cubic centimeters of air 
effect the clouding of the one-half cubic centimeter of 
lime water, the piston rod will stand at 10, which we 
designate as 10 volumes of carbonic acid gas present in 
the incubator. This is, of course, wholly arbitrary, but 
it serves very well to give an indication of the relative 
amount of the carbonic acid gas present. What this 
measurement actually amounts to is this: The fifty 
cubic centimeters of incubator air contains enough car- 
bonic acid gas to cloud one-half cubic centimeters of 
lime water, which is equal to 100 cubic centimeters of 
incubator air clouding one cubic centimeter of lime water. 

We suggest that all incubator tests on carbonic acid 
gas to be made in the future, be made upon this measure- 
ment, as it is very convenient indeed, and serves all prac- 
tical purposes in the best possible way. Some unit of 
measure will have to be decided upon, and as all our 
tests have been made on this, it would only confuse mat- 
ters if any additional standard of measurements were in- 
troduced. 

The lime water which we use is prepared in the ordin- 
ary way, just taking a piece of unslaked lime and dissolv- 
ing as much of it in water as the water will take up per- 
fectly clear, and using the clear part of the water. We 
use the ordinary five cubic centimeter graduate. The 
whole outfit is sold for $5.00 to anyone who is interested 
in these experiments. It is necessary to clean the 

graduate after each test, as more or less clouding will 
be effected, which will interfere with the reading. 

If an ordinary rag will not clean it, use a drop of 
hydrochloric acid, which will clean the graduate in- 
stantly, and it should be well rinsed after cleansing. 

In all our tests the air was not withdrawn from the 
incubator until it had been closed for 2 4 hours. 

23 



THE MOISTURE PRORLEM, 

There is uo end to the theories about moisture in an 
incubator. There seems to be an almost universal o[)in- 
ion that eggs will be helped by being sprinkled, or by 
filling the incubator by some means with moisture. 

Undoubtedly the moisture problem is a very important 
one in artificial incubation, and it is by far the most 
difficult of solution. It is comparatively easy to deter- 
mine the relative amount of carbonic acid gas under a 
setting hen, and it is also comparatively easy to secure 
something of a corresponding amount of this gas in an 
incubator by reducing the air space surrounding the eggs, 
but with the moisture problem it is different. It is al- 
most imi)ossible to find out the relative amount of mois- 
ture surrounding the eggs under a setting hen. The 
space is so very small that it is almost impossible to make 
any test. The wet bulb thermometer is practically inap- 
plicable here. The amount of moisture introduced by 
the wet bulb would interfere with any correct results of 
a test. 

About the only other method available is the use of the 
spiral hygrometers, which are very unreliable at best. 
We have made hundreds of tests of setting hens, using a 
spiral hygrometer, placing it as carefully as possible, and 
after reading it transferring it to an incubator, and intro- 
ducing moisture into the compartment, or withdrawing It 
until we found a corresponding reading, and then compar- 
ing it with our wet bulb instrument. 

There would be only one other way of measuring the 
moisture under the setting hen, and that would be by 
withdrawing a small portion of air, and by analysis de- 
termining the actual percentage of moisture present in 
it. For this we did not possess the necessary instru- 
ments, and it is very doubtful if it would be of very much 
value. The results which we have obtained have been 
variable indeed, ranging as low as 3.5',; of humidity, and 
as high as 60';{. It has been impossible to get almost 
any two readings alike. Perhaps the only actual result 
that is dependable is the fact that in all cases the hu- 
midity of the air surrounding the eggs under the hen 
was considerably drier than the outside air. 

It was also found that the amount of humidity under 
the hen bears no corresponding relation to the humidity 
in the outside air. Some of our tests of hens setting 
practically out of doors, in rainy weather, with the rain 
dropping over their wings, still showed only about 40° 
of humidity over the eggs. But to repeat, none of the 
tests made can be regarded as in any sense absolutely 
accurate, so we have no clue as far as the hen is con- 
cerned, what the amount of moisture should be sur- 
rounding the eggs. Perhaps the safest way is to re- 
gard the lowest reading the most accurate, as nearly all 
instruments register higher than actual humidity. 

When it comes to the incubator it is easy enough to 
determine the relative humidity inside the egg chamber. 
All that is needed is a reliable wet bulb thermometer. 

24 



Place it carefully, and read the difference between the 
dry thermometer, and the wet bulb thermometer, and the 
amount of relative humidity can be readily determined 
by the use of psychro-metrical tables published by the 
United States weather bureau. (A number of so called 
incubator hygrometers are on the market, which pretend 
to give a direct reading of the humidity in the egg cham- 
ber, but these cannot be used for anything like accurate 
work. Some of them do not read low enough, and it is 
doubtful if others are sufficiently accurate. Any hygro- 
meter that does not read as low as 35° is worthless for 
incubator use, and should not be sold for that purpose.) 

For all practical purposes it is much simpler to disre- 
gard the actual relative humidity, but carefully note the 
depression of the wet bulb thermometer. In that way 
all confusion and difficulty is avoided. 

The only method open to determine the right amount 
of moisture for successful incubation, is by repeated ex- 
periments. Our experiments in this line have continued 
for over six years, and hundreds of hatches have been 
carefully noted. We have never found a good hatch 
unless the air in the incubator was comparatively dry. 
The percentage of about 40° or 45° humidity seems to 
give the best results, which is equal to a depression of 
about 18° to 20° on the wet bulb thermometer. Where 
it is possible we prefer to use 20° of depression for 
hatching, i. e., 83° on the wet bulb. We have had uni- 
formly good results at this point, provided all other 
things are right. There is no doubt that a great many 
incubators, and a great many hatches fail because it is 
impossible to get the air dry enough. Of course, on the 
other hand many hatches are spoiled by the air being too 
dry on account of the excessive ventilation within the 
incubator chamber. But it was found in our other ex- 
periments that there must be practically no ventilation o' 
any kind in the incubator chamber, and the air surround- 
ing the eggs must remain perfectly quiet in order to main- 
tain sufficient carbonic acid gas and prevent the formation 
of cripples. This makes the moisture problem a most 
difficult one. Incubators will act as contrary as anything 
that can be imagined in this respect. 

The problem in incubation is to get the air within the 
egg chamber to run about 83°, wet bulb, without ventila- 
tion of any sort. Where this cannot be accomplished the 
hatch will be more or less a failure. Some incubators 
we have had we simply could not use at all. Others of 
identically the same make worked without any trouble. 
Only a very few that we found needed artificial moisture, 
when the machine had been made practically air tight. 

One of our large machines was a constant puzzle to us. 
It contained eight compartments holding 2 000 eggs. 
The compartments are all built identically alike. They 
are all heated in the same manner by one hot water sys- 
tem. They all show the same temperature yet one com- 
partment runs 2 0% higher in moisture than all the others, 
and consequently we cannot use that compartment. We 

25 



have been unable to determine any reason whatever for 
this difference. There are certain seasons of the year, 
however, when all the compartments run alike, and we 
can use the whole machine. This is simply one of the 
instances of the many queer actions with which incu- 
bators confront us. 

We find that a space about twelve inches high from the 
bottom of the machine to the top is necessary to give suffi- 
cient dryness of the air, which has to take up of course 
the evaporation of the moisture from the egg, and still not 
become too highly saturated with moisture. 

We have sometimes found it quite an improvement to 
slip a diaphragm, made of thin muslin, between the eggs, 
and the hot water pipes, thus making two compartments 
in the machine. The diaphragm should be close to the 
pipes. Small openings may then be made through the 
top of the machine into this upper compartment, say one 
or more half inch holes for every 250 eggs. This has 
a tendency to cause a very, very slow movement of the 
air, and as more heat is needed to heat up the incubator 
through this diaphragm, there is more dry air in the ma- 
chine than can otherwise be secured. It seems the small 
opening helps to dry out the air without appreciably af- 
fecting the air below the diaphragm. 

In smaller machines we have found a rather effective 
way in allowing hot air to circulate around the heater, and 
allowing it to open into the upper compartment of the 
machine. This makes the circulation of the air much 
slower since it has no outlet, but it seems to secure the 
dry atmosphere, which is so very essential in the egg 
chamber. 

The moisture in the air of the incubator room has no 
effect on the eggs in the machine. An incubator with 
ventilators open will usually register much drier on blus- 
tering rainy days than on hot, dry, or sultry days. In 
warm weather the incubator ventilators do not work at 
any rate, for if there is not much difference in the tem- 
perature outside the machine, no air will pass through. 
It may be given as a safe rule never to put water in an 
incubator, on hot sultry days. If ever any moisture is 
needed, it is in winter, or on windy days. Those are 
the times when the incubator is actually too dry. This 
will sound strange, to the inexperienced, but place a re- 
liable hygrometer in the incubator on hot, dry days, and 
you will find a very high humidity. The opposite wnll 
be found on cold days, even if they are rainy. More 
air is sucked through the incubator on cold, windy and 
blustering days, which causes it to be excessively dry. 
Sprinkling the floor of the incubator room has not the 
slightest effect on the moisture within the machine. The 
effect of too much moisture in the incubator will be that 
many chicks are dead in the shell, as many as one half 
or more sometimes. 

A rough distinction may be made in this way: If the 
chicks that hatch are scrawny little things with protrud- 
ing entrails, or unabsorbed yolk, there was too much yen- 

26 



tilation. If the chicks that hatch are fairly good and 
large in size, the chicks dying in the shells is due to too 
much moisture. Both faults cause chicks to die in the 
shell, and both must be avoided. However, it is safe 
to say ten times as many chicks die in the shells from 
too high humidity, i. e., too much moisture, than for lack 
of it. 

If moisture is actually needed, the best way to intro- 
duce it is a wet sponge placed on the eggs. Water pans 
may be placed in the bottom, but this does not usually 
have much eifect. 




2. P. Cook's 

simplified 
Hygrometer. 

Price, $1.00. 



B Wei- Bulb P5>jLhro>^itle«- 

p. Cook's continuous reading 
Hygrometer. Price, $3.00. 



DIRECTIONS FOR USING P. COOK'S HYGROMETER. 

Our hygrometer consists of two accurate thermometers, 
one of which has a muslin wick connected with a water 
cistern, attached to it. The whole instrument is placed 
in the machine like an ordinary thermometer. The evap- 
oration of water from the wick around the bulb of one 
thermometer causes this bulb to cool in proportion to the 
amount of evaporation. The drier the air in the incu- 
bator, the more rapidly will it evaporate water from 
the wick and thus cause the wet bulb to read lower than 
the dry bulb thermometer. Indirectly, the difference be- 
tween the two thermometers indicates the dryness of the 
air. This is the method used in the U. S. Weather Bu- 
reau, and it has published elaborate tables from which 

27 



the relative per cent of humidity can be learned if once 
the depression of the wet bulb thermometer is known. 
We print here a part of these tables as far as they are 
of use for incubator purposes. For instance, if the dry 
bulb stands at 103 and the wet bulb at .S3, there is twenty 
degrees difference, i. e., there is twenty degrees depres- 
sion on the wet bulb. The wet bulb thermometer is 
technically called a psychrometer. From the table it 
will be seen that there is 42 ])er cent relative humidity 
in this case. Or if the dry bulb registers 100 degrees and 
the Psychrometer S2 degrees, there is IS degrees depres- 
sion, and it is found from the table that in this case there 
is 46 per cent humidity. 

rSY( H ROMKTER TABLES. 



iture of 

rmometei 




Deiiise* of DepreuioQ of Psychi otnetet 


1' 


16 


17 


18 19 


20 


21 22 


98 
100 
102 




50 
51 
52 


48 
49 
49 


45 
46 
47 


43 
44 
45 


40 38 

41 39 

42 40 


36 
37 
38 


B r 


103 


52 

53 
53 


49 

50 
51 


47 


45 


42 40 


38 




104 
106 


48 
49 


46 
46 


43 
44 


41 

42 


39 

40 





For practical purposes it is much easier, however, to 
disregard these moisture percentages. It is enough to 
know that when your thermometer reads 103 degrees and 
the Psychrometer 83 to 85, your machine is working 
properly and no further attention need be paid to it. 

Ordinarily, if an incubator is once started righi, and 
our other instructions for closing the ventilators, etc., 
have been followed, there will be no need to use a hygro- 
meter, as the moisture does not generally vary much dur- 
ing a hatch. Nevertheless, it will soon pay to be in 
possession of a hygrometer, but as our larger instrument 
costs three dollars, it is too costly for the man who has 
only a small machine. We have, therefore, designed a 
much cheaper instrument, which is just as reliable, but 
takes a little more trouble to use it. This is simply an 
accurate Thermometer reading down to 75 degrees. A 
thin piece of muslin is tied around the bulb, this is 
dipped in luke-warm water and then inserted into the 
incubator, through a hole bored in the door. It is left 
there for ten minutes and then partly pulled out to see 
how low it reads. Its lowest reading, just before the 
muslin is completely dried out is its correct reading. A 
number of readings should be taken, the lowest one is the 
most correct. The incubator should not be opened be- 

28 



fore inserting the Psychrometer. Remember the differ- 
ence between it and your thermometer indicates the mois- 
ture. If your incubator stands at only 100 degrees, then 
80 degrees on the Psychrometer indicates proper hatch- 
ing humidity. It is twenty degrees difference that is 
required. Use your table unless your incubator stands 
at 103 degrees. The simplified instrument is sold for 
$1.00, and will be found a most excellent help. Only one 
instrument is needed no matter how many incubators 
are used, as moisture does not need to be taken oftener 
than in the beginning and two or three times during the 
hatch. 

We are aware that these directions require much drier 
air thany many manufacturers advise, but we have in- 
quired among many hatchers and we have not heard of 
one of them that has succeeded in securing good hatches 
at any other percentages the great claims of some 

hygrometer makers notwithstanding. It should be remem- 
bered however, that our figures are for incubators with 
perfectly still air, i. e., without any ventilation. Still 
air is not nearly as drying as air in motion. 

From our standard hatching table it will be seen that 
during the exclusion of the chicks we allow 9 2 on the 
Psychrometer. This is normal and need not be changed 
unless chicks are breathing heavily or standing with their 
mouths open. This indicates too much moisture, as often 
as too much heat. Ventilators must then be opened, or 
if the machine has no ventilators, open the doors for a 
minute and let the moisture escape. As soon as the 
hatch is over, see that enough air is admitted into the 
machine to dry out and fluff up the chicks properly. 

Sprinkling the eggs will never do them any good; its 
only effect is to chill them, and if they hatch at all, they 
hatch in spite of it. In fact nothing that is done to the 
eggs for a few minutes during the last week, helps tliem 
in any way. We seldom ever find any need of moisture 
during hatching time, only if something is seriously 
wrong with the incubator moisture will help to over- 
come its defects. Shut your machine tight until pipping 
time, and do not open it till chicks begin to show signs 
of the need of more air. 



Some Tyi)ical Tests of Moisture Under Setting Hen. 

7 a. m. Outside air near hen's nest temperature 5 2 
degrees, moisture full saturation or 100 per cent, moisture 
under the hen, 49 per cent. 12, noon, temperature out- 
side, 74 degrees; moisture 5 8 per cent; moisture under 
the hen, 40 per cent. 5 p. m. Temperature 66, moisture 
61 per cent. Moisture under the hen 40 per cent. In all 
the numerous tests we have made, we always found much 
less moisture under the hen than in the air around her. 
As she heats the air in her nest, it would naturally reg- 
ister drier than the outside air, unless she supplied mois- 
ture from her body, but as all tests show this is not the 

29 



case. The hen does not sweat through her skin and it 
seems that her feathers asbsorb the evaporation from 
the eggs. We had one White Rock hen sitting on damp 
ground and the moisture under her always ran between 
(>0 to 65 per cent, but all the germs rotted in the shell, 
only three lived till the 21st day, but did not hatch. The 
other tests above given are from hens that brought oCf 
normal hatches. 

Where we made daily tests for moisture, the hens al- 
ways brought off poor hatches, due no doubt to disturb- 
ing the hens too much. 



HELPING CHICKS OUT OP THE SHELL. 

There is little use to help chicks out of the shell when 
they have not been properly incubated, but in the moult- 
ing season we have sometimes found that the stragglers 
can be helped to advantage. A chick should never be 
helped too early, and unless it is plump and in every re- 
spect perfect when helped out, it is not worth anything 
In the time that eggs are naturally fertile, all chicks will 
usually pop out without any help. Chicks too weak to 
get out then is a sure indication of faulty incubation. No 
chicks should be helped out until the hatch is nearly 
over. 



TYPICAL WEIGHTS OF A GOOD HATCH. 

100 Fresh eggs, 11% lbs. 
100 clear eggs 10 ibs., 6 oz. (1.5 days in incubator), 
at 85 Psychrometer reading.) 

100 chicks 8 lbs., 1 oz. 
GOOD HATCHES ATTRIBVTED TO WUONG CAUSES. 

Here it is well to point out that frequently good hatches 
are attributed to wrong causes. Mr. "A" puts a pan of 
water under his eggs, the last few days, or sprinkles 
them or gives more ventilation, etc., and has a good 
hatch. He concludes this is the thing to do. But it may 
have had nothing whatever to do with the good hatch. 
The fact is that strong eggs hatch well in spite of a 
good many things. We dropped a tray of eggs once. 
Two-thirds of the eggs cracked. (16th day of incuba- 
tion.) We patched them up with celloidin and they 
all produced remarkably strong chicks. Nevertheless, 
cracking eggs is not the best way to hatch them. It 
should be remembered, the critical period of incubation 
are the first six days, and it may almost be said, that 
it does not matter what happens after that. Certainly 
eggs will stand quite a lot of abuse after that and still 
hatch well. So far as ventilation is concerned, it may 
be said that most arrangements do not work, which is 
their recommendation. If the ventilators of the incu- 
bator actually get to work, then they produce mischief. 
If the incubator is placed in a room where the air is 
still, there is but very little ventilation going on inside 
the machine, but if the air of the room gets in motion, 

30 



it will be sucked through the ventilators of the incubator, 
and a spoiled hatch will follow. Too much ventilation 
produces small, scrawny chicks with protruding bowels, 
etc. A spoiled hatch from too much ventilation is about 
the sickliest sight imaginable. The glowing claims of 
incubator manufacturers that their machines change the 
air ever so often, are fortunately not often true, but 
when they are true their machines fail to hatch. 

It is not known whether the amount of carbonic acid 
gas has anything to do directly with hatching, for it 
varies greatly under different hens. It may be that all 
that is required is absolutely still air in the incubator. 
In still air the gases do not diffuse very readily. We 
found in one machine that had eggs only on one tray, 
twice as much carbonic acid gas as on the other tray 
without eggs. As a rule, there is a little more at the 
bottom than near the top of the machine, which is 
natural, since the carbonic acid gas is heavier than air. 
The fact remains, however, that eggs under the hen are 
incubated under the pressure of a very large amount of 
carbonic acid gas. This was found true even of a tiny 
bantam hen that weighed only about one pound, but the 
percentage of carbonic acid gas under her was as great 
as under the large hens. This proves conclusively, that 
there is no so-called ventilation under the hen, nor any 
diffusion of the natural gases, or the carbonic acid gas 
would have been carried away. 

The chief value of these measurements, as we regard 
it, is in the fact that they pointed out the right way to 
build an incubator, i. e., one that surrounds the eggs with 
still air, and thus produces conditions similar to those 
under the hen. There is, of course, no reason to believe 
that carbonic acid gas itself helps the hatching. It is a 
waste product of the respiration of the embryo but em- 
bryonic respiration is a decidedly different process from 
respiration of the full grown hen, and a large amount 
of carbonic acid gas may not be detrimental, or it may 
have a sort of symbiotic action, but such consideration 
we may leave to the professional biologist. 

Ordinarily the user of the incubator need not test the 
carbonic acid gas. Let him follow our directions in con- 
structing his machine, and he will not generally experi- 
ence trouble. However, the carbonic acid test is the only 
reliable guide to the ventilation. 



METHOD OF HATCHING IN P. COOK'S MAMMOTH 
HATCHERY. 

(The method here given has reference to incubators 
sold commonly to the public, as this will be of great use 
to persons who already possess incubators. The prin- 
ciple is exactly the same as that followed in Mr. Cook's 
own mammoth machines.) 

The first thing that is done is to see that the incubator 
is in good working order, the lamp burning properly and 
lamp fountain not leaking and thermostat in perfect 

31 



order. Then the door Is examined, and if it does not 
fit air-tight, strips of felt are nailed around the edges, 
so as to make it fit tight. One or two layers of burlap 
or cotton batting are placed in the bottom of the ma- 
chine to make it warm enough below the eggs. 

The temperature at the bottom of the incubator should 
never be allowed to fall much below 90 degrees. If it 
is colder than that cripples are sure to result. If the 
machine has nursery diawers, it is best to fill these up 
with straw or cotton for the first two weeks at least. If 
the machine has no nursery the temperature at the bot- 
tom of the egg-tray should be at least 100 degrees. 

When the machine is heated up, the thermometer is 
placed in position where the top of the eggs would come 
and the regulator adjusted to hold the machine at 103 
degrees. The machine is kept going for a day or so with 
ventilators open in order to dry it out. Then a hygro- 
meter is also placed into it and watched till it sinks to 
83 degrees. It may take several days to dry out the ma- 
chine sufficiently. Then the ventilators are all closed 
and the hygrometer read again. If it stands between SO 
and 83 degrees, it is all right. If it stands above that, 
the machine must be further dried out. There is not 
much probability of a good hatch if the hygrometer at 
the beginning of a hatch remains as high as S7 for more 
than a day. 

We had to run one machine for three weeks, before it 
became dry enough for hatching. If you cannot make 
your machine dry enough do not waste your eggs on it. 
We have never come across a machine too dry, if all its 
ventilators are closed. 

Next the egg trays are taken and fitted with a me- 
chanical turning rack as described elsewhere. The eggs 
are placed on the tray with the turning rack in position. 
They are laid flat on the side and not crowded. You can 
get more eggs into the machine by standing them on 
edge, or even by doubling them up, and the strong 
eggs will hatch that way, but the weaker ones will die 
in the shell. But remember, what is not good for the 
weaker eggs, is no benefit to the stronger ones either. Do 
not begin the poultry business by abusing your chicks 
before they are born. It is knocking your profits with a 
club on the head. 

When the eggs are on the tray, thermometer and hygro- 
meter are then placed in position and all outgoing venti- 
lators are shut tightly. The best way to do this is to 
stuff a tuft of cotton into the holes. It need not be 
stuffed very tightly. Those machines that have the air 
intake over the lamp or around the heater, need only 
to have the outlets closed, for as soon as these are closed 
no more air passes through them into the machine. On 
other machines all ventilators must be closeor. 

The eggs are turned by the mechanical turner after 
six hours and after that every twelve hours apart, but 
under no conditions must the machine be opened for the 
first 72 to S4 hours. 

32 



On the morning of the fourth day the incubator is 
opened for the first time and the eggs are talten out 
and aired for about ten minutes. They are also tested 
for infertiles at this same time. Then the eggs are re- 
turned to the incubator and turned mechanically twelve 
hours after this without opening the machine. At the 
next twelve hours the eggs are aired again for ten minutes 
and so on till the twelfth day. After that they are aired 
15 minutes, but never under any circumstances is the 
machine opened more than once a day. This method, 
ventilators closed, eggs aired only once a day, but turned 
twice daily, and 83 degrees on the psychrometer, we 
have found an unfailing cure for chicks dying in the 
shell. But no one of these details must be omitted, or 
the hatch may be spoiled. 

On the 18th day the machine is closed, but small ven- 
tilators may be left open, if your incubator room is free 
from drafts. There will be no trouble, if these directions 
have been followed, with chicks getting out of the shell. 
There will be a downy lot of fine fluffy balls, as lively as 
can be wished in your machine next morning. 

In one respect nothing is so important as this closing 
of the ventilators, especially if your incubator stands 
in a room that has the least draft in it. Eggs will not 
hatch to the best advantage except in absolutely still air. 
For that reason taking eggs out of an incubator twice 
a day is detrimental. Only the strong eggs will stand 
it, the weaker ones will die in the shell. Do not worry 
about the need of fresh air. There is rar more oxygen 
in the incubator than the eggs will ever need, as is shown 
conclusively by the carbonic acid gas test. It is true the 
carbonic acid gas may be a very variable quantity, de- 
pending upon the number of eggs in the incubator, etc., 
but the still air is the thing of highest importance. We 
know of hundreds of incubators that miserably failed to 
hatch with the manufacturer's fresh air directions v\rhich 
became first-class hatchers by simply nailing up the ven- 
tilators and using a mechanical turning tray. 

During the proper season of the year we find that gen- 
erally every germ alive at the 17th day hatches a perfect 
chick. Even in the molting period we have had many 
perfect hatches by this method, but occasionally some 
chicks die in the shell then, however, we seldom find over 
ten per cent of dead chicks even at that time. Of course 
no account is taken of germs that die before the seven- 
teenth day. Sometimes there are many of these, but the 
fault lies with the eggs in such cases and neither hen nor 
incubator could hatch them. 



HATCHABLE EGGS. 



There is a large difference of opinion as to which is 
to be considered a fertile egg. Breeders in selling eggs 
usually follow the practice of guaranteeing a certain 
percentage of fertile eggs, meaning that they will replace 
any perfectly clear eggs below their guarantee. There 
are, however, always a certain number of eggs with im- 

33 



perfect germs or weak germs, or whatever they may be 
called. None of these imperfect germs can be expected 
to hatch. Neither hen nor incubator could do anything; 
with them. Some of these germs do not aevelop any 
farther than simply to make a bloody streak through 
the yolk of the egg. Others grow longer. Some live as 
long as the 13th and 14th day. In all these cases the 
germ of the egg has been faulty, and it is impossible to 
hatch such eggs. The proportion of these eggs depends 
upon the vigor of the fowls, and to some extent also on 
the season of the year. It is a good plan to test all the 
eggs in an incubator on the 17th day. All of the em- 
bryos dead at that time should be removed. If all the 
chicks alive in the shell on the 17th day hatch, the hatch 
may be called a perfect hatch, as that is all that can pos- 
sibly be expected to hatch. But the great great difficulty 
with incubators has been that the chicks die in the shell 
after the 17th day. If any large proportion of chicks die 
in the shell after the 17th day we consider it the fault 
of the incubators, not of the eggs. After chicks have been 
developed up to that stage they would probably hatch 
if they had been incubated right. Our experience has 
been that if everything has been right during 
the period of incubation practically all the chicks alive 
at the end of the 17th day will hatch. 



MAMMOTH AND COMPARTMENT MACHINES. 

We have spent a great deal of money in the attempt 
to build a large compartment machine heated by only 
one heater and capable of continuous hatcning. Such 
a machine is evidently very desirable for a large hatch- 
ing plant, but we have met with only moderate success 
in this direction. It is easy enough to construct a ma- 
chine with any number of compartments to hatch prop- 
erly if the entire machine is filled with eggs at the same 
time. Then all the compartments require the same 
amount of heat and the entire machine can easily be 
regulated by one thermostat. But difficulty arises when 
eggs of different periods of incubation are placed in dif- 
ferent compartments. The eggs much ahead generate 
a good deal of their own heat and have to be in cooler 
compartments. It is very diflicult to remove surplus heat 
from such compartments without interfering with the 
necessary moisture and carbonic acid gas conditions. The 
easiest way to remove heat from a compartment would 
be by letting it escape through ventilators, but this is 
not permissable, for ventilation spoils the hatch. Stop 
cocks or other methods must be used, which involve a 
great deal of expense. It can no doubt be done, but we 
have abandoned it for our own use. We have found 
it much the cheaper method to build different incu- 
bators. One machine can be used for the first week, an- 
other for the second and a special machine can be built 
for the last week with conveniences to take care of 
the chicks for hatching. 

34 



Our machines are 22 feet long and four feet wide and 
in this size we have found no need for more than one 
thermostat for each machine. Each machine is built 
with eight compartments independent of each other. 



NURSERIES. 



We have used machines with nurseries in nearly all 
our experiments. We do not know of how much real ad- 
vantage they are. In a big hatch chicks seem to have a lit- 
tle more elbow room as they are away from the shells. 
Many machines are made with drawers, but these are 
not always an advantage. If a machine is made with 
drawers, it should be so made that the egg tray is placed 
on the drawer and always comes out with it. If the 
drawers are made to slide in under the tray, there is 
always trouble. As soon as the drawer is pulled out 
a number of chicks will jump over the back of the drawer 
and others raise their head and you can neither shut nor 
open the machine or get the chicks. We prefer no draw- 
ers at all unless the egg tray comes out with the drawer. 



DISINFECTING INCUBATOR. 

At least every third hatch an incubator should be 
thoroughly disinfected. The trays and bottom should be 
thoroughly cleansed'. They can be washed with almost any 
good disinfecting fluid or sulphur may be burned in it. 
This last is the most effective method, but it will require 
some days of airing before you can get the sulphur out 
again. However, it is not necessary to get all the sulphur 
smell out. We have had good hatches with the sulphur 
smelling strongly all during the incubation. 

The incubator is a splendid hatcher of all kinds of 
germs and white diarrhea may be caught in the incubator. 

On the other hand, the incubator should not be blamed 
for chicks dying after they are some days old. If the 
chicks are big and strong when hatched, you may be as- 
sured that the incubator has done its part. After that 
the fault lies with the brooding. 



INCUBATOR HOUSES AND CELLARS. 

Incubator may be placed in any room that will shel- 
ter it, but a basement or cellar that is light and cheery, 
and not too damp is very desirable, for the temperature 
of such a place is not subject to as much variation as an 
ordinary room. The most desirable temperature for an 
incubator room is between sixty and seventy degrees. The 
most important item, however, is, that it be well venti- 
lated, but absolutely free from draft. Nothing works 
so much mischief in an incubator room as drafts. In a 
perfectly quiet room it is not always necessary to resort 
to the mechanical turning tray. Eggs will fairly well 

35 



^ad 14 1911 



stand opening the machine twice a day for turning, only 
for the one turning the eggs must be returned as soon as 
possible to the machine. But even in the best incubator 
room a strict adherence to our method will be found to 
pay well. 

A cellar three feet deep with cement floor and walls 
and the rest of the building above ground, is the ideal for 
an incubator house. It should be kei)t dry. Never 
sprinkle the floor. 

It is immaterial whether lamps, gas or coal, etc., is 
used for heating incubators, but the fumes should be 
carried off through chimneys. 



CHICKS DYING IN KKOODEK. 

It is not always easy to raise a big flock of chicks artifi- 
cially, and while it does not belong here, we may as well 
point out one great means of saving chicks. People have 
become so accustomed to the necessity of disinfection 
that they believe if they could only kill all the germs, 
their chicks would do well, but they forget that there 
are as many if not more, beneficial germs as there are 
disease germs. Disinfection kills both the good and bad 
germs. The real remedy is not always more disinfec- 
tion, but better natural conditions for the chick. Prof. 
Metchnikoff, head of the Pasteur Institute in Paris 
hatched and tried to rear chicks under absolutely germ- 
proof conditions, but found that his chicks would dwindle 
away and die in a few weeks. Afterwards he allowed 
his chicks to come into contact freely with the ordi- 
nary dunghill bacteria and they were thriving as they 
should. The intestinal canal is inhabited by a number 
of bacteria that aid materially in digestion, and the en- 
tire absence of these causes many chicks to die appar- 
ently without any cause. 

One of our neighbors, a famous breeder of Barred 
Rocks, has for years claimed that the only sure way to 
prevent white diarrhea in chicks is to feed them a liberal 
supply of maggots. He has been a steady customer for 
the rotten eggs from our hatchery. He exposes them 
to the flies for a day and then lightly buries them. Shortly 
there is as big a lot of wrigglers as any old hen would 
want. He feeds these maggots regularly, and certainly 
raises magnificent birds on them. It is probably safest 
to use maggots thus produced under ground, for if the 
eggs were not buried, there might be ptomaines de- 
veloped. 

In everything the poultryman should remember that 
he cannot far transgress nature with immunity. If 
chicks are once well hatched, then look to your brooding 
system. 

36 

Li, My 'II 



Successful 
Incubation 



By P. COOK 




The WEIMAR PRESS, Los Angeles, Cal. 



LIBRARY OF CONGRESS 



002 857 364 9 



